Maybe the difference in some sensor benchmarks are small (remember: DXO differences of less than 5 points are not visible to naked eye). But there is more than this when comparing xxxD and xxD or even xD series. It boils down again whether one can pinpoint the shortfalls of one body and see the solution to it in a newer / higher end body. If not, then no point ogling around. Sadly, most people do it the other way around: first selecting the body then trying to justify will lots of energy and emotions ...Agreed. No point jumping from crop to another crop. The differences are too minimal.
Was there a smiley missing? I guess soTS, what Yr friend say about better colors in the crop cam is crap la. U wan better colors, change the brand.
A few clicks in any decent post processing tool will make a bigger difference than the esoteric discussion about Nikon colours, Canon skin tones, Pentax Pink ... HDR tools make it easy to overcome the limitations in Dynamic Range for a single image. Some are even built into the cameras. Continue at lib.